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NASA NTRS2019

Improving the Nuclear Launch Approval Process; Progress and Plans

Launches involving radioisotope power systems (RPS) or radioisotope heater units (RHU’s) must comply with a number of different statutory, regulatory, and administrative requirements. While some of these are well defined, others have been carried out on the basis of past practice rather than a set of formal standards. In addition, some of the requirements reference outdated standards and are in need of updates. The overall process is also time consuming and expensive. This paper describes efforts by NASA, the Department of Energy (DOE) and others to make improvements to the process while maintaining safety and environmental protection.

McCallum, Peter↗

NASA NTRS1986

Independent Orbiter Assessment (IOA): Analysis of the extravehicular mobility unit

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) are presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items (PCIs). To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. This report documents the independent analysis results corresponding to the Extravehicular Mobility Unit (EMU) hardware. The EMU is an independent anthropomorphic system that provides environmental protection, mobility, life support, and communications for the Shuttle crewmember to perform Extravehicular Activity (EVA) in Earth orbit. Two EMUs are included on each baseline Orbiter mission, and consumables are provided for three two-man EVAs. The EMU consists of the Life Support System (LSS), Caution and Warning System (CWS), and the Space Suit Assembly (SSA). Each level of hardware was evaluated and analyzed for possible failure modes and effects. The majority of these PCIs are resultant from failures which cause loss of one or more primary functions: pressurization, oxygen delivery, environmental maintenance, and thermal maintenance. It should also be noted that the quantity of PCIs would significantly increase if the SOP were to be treated as an emergency system rather than as an unlike redundant element.

Raffaelli, Gary G.↗

NASA NTRS1990

Diamond Coatings

Advances in materials technology have demonstrated that it is possible to get the advantages of diamond in a number of applications without the cost penalty, by coating and chemically bonding an inexpensive substrate with a thin film of diamond-like carbon (DLC). Diamond films offer tremendous technical and economic potential in such advances as chemically inert protective coatings; machine tools and parts capable of resisting wear 10 times longer; ball bearings and metal cutting tools; a broad variety of optical instruments and systems; and consumer products. Among the American companies engaged in DLC commercialization is Diamonex, Inc., a diamond coating spinoff of Air Products and Chemicals, Inc. Along with its own proprietary technology for both polycrystalline diamond and DLC coatings, Diamonex is using, under an exclusive license, NASA technology for depositing DLC on a substrate. Diamonex is developing, and offering commercially, under the trade name Diamond Aegis, a line of polycrystalline diamond-coated products that can be custom tailored for optical, electronic and engineering applications. Diamonex's initial focus is on optical products and the first commercial product is expected in late 1990. Other target applications include electronic heat sink substrates, x-ray lithography masks, metal cutting tools and bearings.

Source record↗

NASA NTRS2009

Hypervelocity Impact Performance of Open Cell Foam Core Sandwich Panel Structures

Metallic foams are a relatively new class of materials with low density and novel physical, mechanical, thermal, electrical and acoustic properties. Although incompletely characterized, they offer comparable mechanical performance to traditional spacecraft structural materials (i.e. honeycomb sandwich panels) without detrimental through-thickness channeling cells. There are two competing types of metallic foams: open cell and closed cell. Open cell foams are considered the more promising technology due to their lower weight and higher degree of homogeneity. Leading micrometeoroid and orbital debris shields (MMOD) incorporate thin plates separated by a void space (i.e. Whipple shield). Inclusion of intermediate fabric layers, or multiple bumper plates have led to significant performance enhancements, yet these shields require additional non-ballistic mass for installation (fasteners, supports, etc.) that can consume up to 35% of the total shield weight [1]. Structural panels, such as open cell foam core sandwich panels, that are also capable of providing sufficient MMOD protection, represent a significant potential for increased efficiency in hypervelocity impact shielding from a systems perspective through a reduction in required non-ballistic mass. In this paper, the results of an extensive impact test program on aluminum foam core sandwich panels are reported. The effect of pore density, and core thickness on shielding performance have been evaluated over impact velocities ranging from 2.2 - 9.3 km/s at various angles. A number of additional tests on alternate sandwich panel configurations of comparable-weight have also been performed, including aluminum honeycomb sandwich panels (see Figure 1), Nomex honeycomb core sandwich panels, and 3D aluminum honeycomb sandwich panels. A total of 70 hypervelocity impact tests are reported, from which an empirical ballistic limit equation (BLE) has been derived. The BLE is in the standard form suitable for implementation in risk analysis software, and includes the effect of panel thickness, core density, and facesheet material properties. A comparison between the shielding performance of foam core sandwich panel structures and common MMOD shielding configurations is made for both conservative (additional 35% non-ballistic mass) and optimistic (additional mass equal to 30% of bumper mass) considerations. Suggestions to improve the shielding performance of foam core sandwich panels are made, including the use of outer mesh layers, intermediate fabric/composite layers, and varying pore density.

Ryan, Shannon↗

NASA NTRS2019

The "Space Activity Suit" - A Historical Perspective and A Primer on the Physiology of Mechanical Counter-Pressure

Since the 1950s, mechanical counter-pressure (MCP) has been investigated as a possible alternative design concept to traditional extra-vehicular activity (EVA) space suits. While traditional gas-pressurized EVA suits provide physiological protection against the ambient vacuum by means of pressurized oxygen to at least 3.1 pounds per square inch absolute (160 millimeters of mercury), MCP provides protection by direct application of pressure on the skin by a fabric. In reviewing the concept, MCP offers distinct potential advantages to traditional EVA suits: lower mass, reduced consumables, increased mobility, increased comfort, less complexity, and improved failure modes. In the mid 1960s to early 1970s, Dr. Paul Webb of Webb Associates developed and tested such a suit under funding from NASA Langley Research Center. This "Space Activity Suit" (SAS) was improved many times while testing in the laboratory and an altitude chamber to as low as 0.3 pounds per square inch absolute (15 millimeters of mercury). This testing, and the reports by Webb documenting it, are often presented as evidence of the feasibility of MCP. In addition, the SAS reports contain a wealth of information regarding the physiological requirements to make MCP work at the time, which is still accurate today. This paper serves to document the Space Activity Suit effort and analyze it in today's context.

McFarland, Shane M.↗

NASA NTRS2019

Mechanical Counter-Pressure EVA Suits: NASA Outlook and Development Strategy

Since the 1950s, mechanical counter-pressure (MCP) has been investigated as a possible alternative architecture to traditional extra-vehicular activity (EVA) suits. While traditional gas-pressurized EVA suits provide physiological protection against the ambient vacuum environment by means of pressurized oxygen to at least 3.1 psid, MCP provides protection by direct application of pressure on the skin by a fabric. In reviewing the concept, MCP offers distinct potential advantages to traditional EVA suits: lower mass, reduced consumables, increased mobility, increased comfort, less complexity, and improved failure modes. In addition, as basic feasibility was established in the 1960s with the successful testing of the Space Activity Suit, MCP seems poised to inevitably supplant traditional EVA architectures with a modest degree of concentrated development. However, as they say, "The devil is in the details". This paper serves as a comprehensive summary of the technical work that has been completed related to MCP from 1960 to 2019, the technical gaps that need to be closed to facilitate a flight-capable design, and outlines an overall development strategy that NASA feels would best address these gaps moving forward.

mechanical counter-pressure↗

NASA NTRS2000

Development of a Reference Dose for Perchlorate: Current Issues and Status

The perchlorate anion (ClO4) is typically manufactured as the ammonium salt. The most common use of ammonium perchlorate is in the aerospace program as a component of solid rocket fuel. The perchlorate anion is exceedingly stable under environmental conditions and has been found in ground and surface waters in CA, NV, UT, AZ, TX, AK, NY, MD, WV and FL. The National Center for Environmental Assessment (NCEA) of the U.S. Environmental Protection Agency (US EPA) is in the process of developing an oral reference dose (RfD) for perchlorate. An oral RfD is a body-weight-adjusted dose that can be consumed daily over an entire lifetime with the expectation of no adverse health effects. Once developed, the new RfD will be used by US EPA as the basis of a safe-drinking-water level (SDWL) guideline. US EPA and regional regulatory agencies will then jointly or separately propose clean-up action levels for ground and surface waters at contaminated sites. The toxicological database on CIO4- as of March 1997 was determined by an expert peer-review panel to be inadequate for the purpose of deriving an oral RfD. For example, little or no experimental data existed on the subchronic, reproductive, or developmental toxicity of perchlorate. To fill gaps in the toxicological database, eight animal studies were designed by a government-industry consortium that included US EPA and AFRL. These studies were performed in 1997-1998. It has been known for many years that in the thyroid, high doses of perchlorate block the function of iodide by competing for iodide binding sites. Perchlorate was used in the 1950s-60s as a treatment for Graves' disease (a hyperthyroid condition). Because of what was already known about the pharmacological mode of action of perchlorate, specific concerns addressed in the design of the recent animal studies included the potential for developmental toxicity, notably neurological development. Upon review of complete study reports from four of the studies and incomplete data from the other two, US EPA/NCEA issued a document in December 1998 stating that the critical effects were hormone and histology data from the neurodevelopmental/behavioral toxicity study that had been performed in rats; an RfD was proposed based upon the observation of thyroid-follicular-cell hypertrophy in the 5-day-old pups (PND) of dams given perchlorate in drinking water at 0.1 mg/kg-day (the lowest dose tested) in this study. US EPA/NCEA also focused attention on a nonsignificant increase in motor activity observed in 14-day-old male pups in the same study at the same dose. In February 1999, a public workshop was convened at which an external peer-review panel determined that there was still insufficient data to support the development of a RfD. Additional studies were recommended. Since that time a clinical study revealed significant depression of thyroidal uptake of iodide in volunteers receiving potassium perchlorate at 10 mg/day for 14 days. Follow-up studies currently underway include a pathology working-group review of histology slides from the all of the previous studies, a motor activity study similar to the first behavioral study, an additional immunotoxicity study, male and female rat kinetic studies, a hormone interlaboratory study, and an effects study for thyroid and brain in developing rats. These studies are expected to be complete by mid-2000. A clinical study is planned to determine inhibition of iodide uptake and kinetic parameters in humans following 14-day perchlorate ingestion. The kinetics studies will provide data for developing physiologically based pharmacokinetic (PBPK) models for rats and humans needed to establish the RfD.

Pleus, R. C.↗

NASA NTRS1995

Prosthesis Material

FAB/CAM, a subsidiary of the Harshberger Prosthetic and Orthotic Center, Inc., approached Marshall for help in replacing the heavy, fragile plaster they used to produce master molds for prosthetics. Concurrently, Marshall and Martin Marietta were creating a commercial derivative of the foam insulation used to protect the Space Shuttle External Tank from excessive heat. FAB/CAM found the foam blanks to be lighter, cheaper and easier to manufacture than plaster, resulting in lower costs to the consumer. Martin Marietta markets the foam system, MARCORE, for the prosthesis market. The system also has commercial potential in high temperature insulation and structural applications.

Source record↗

DOE OSTI2025

Many-Body Quantum Catalysts for Transforming Between Phases of Matter

A catalyst is a substance that enables otherwise impossible transformations between states of a system, without being consumed in the process. In this work, we apply the notion of catalysts to many-body quantum physics. In particular, we construct catalysts that enable transformations between different symmetry-protected topological (SPT) phases of matter using symmetric finite-depth quantum circuits. We discover a wide variety of catalysts, including GHZ-like states that spontaneously break the symmetry, gapless states with critical correlations, topological orders with symmetry fractionalization, and spin-glass states. These catalysts are all united under a single framework that has close connections to the theory of quantum anomalies, and we use this connection to put strong constraints on possible pure- and mixed-state catalysts. We also show how the catalyst approach leads to new insights into the structure of certain phases of matter, and to new methods to efficiently prepare SPT phases with long-range interactions or projective measurements.

quantum many-body systems↗

NASA NTRS1994

Passive Vibration Isolator For Experiments

Passive isolator reduces natural vibrational frequency of platform to less than 1 Hz - well below frequencies of vibration induced by human activity. Biological, crystal-growth, and other experiments mounted on platform protected against disturbances by technicians working in vicinity. Designed for use in microgravitational environment of spacecraft. Modified version designed for use on Earth by including components counteracting steady normal Earth gravitation. Consumes no electrical power, simple, and inexpensive.

Naumann, Robert J.↗

NASA NTRSDate not supplied

Excavation of Exploration Toilet Fecal Canister from ISS Operations and Future Mission Impacts

Space exploration requires accommodations for crew members similar to survival on Earth including food and water, clothing, and protection from the environment. In addition, allowances for biological processes such as breathing, defecation and urination must be provided. In a micro-gravity environment, these are particularly challenging. Optimizing the consumables needed for these activities is a vital part of the spacecraft design as well as providing mass/volume for science cargo and the crew needs such as food and clothing. NASA has collected use rates for the consumables needed for defecation and urination over the decades of human-rated space travel. Most recently, the exploration toilet demonstration on International Space Station (ISS) provided data on defecation in the form of a returned canister which collected 13 days of fecal deposits, wipes, gloves and compaction plates. The canister was excavated by a dedicated team of engineers at Johnson Space Center (JSC) to provide the latest information on deposit size and weight, number of wipes and gloves used, and compaction efficiency which directly relates to the number of canisters needed. Although this is only one canister, the data found has been directly applied to manifest decisions for the Orion Artemis-2 mission. Future canisters will add to this data set. Details on what was found and how it compares to historical numbers as well as how it will be used for exploration missions will be covered in this paper.

Toilet↗

NASA NTRSDate not supplied

Excavation of Exploration Toilet Fecal Canister From ISS Operations and Future Mission Impacts

Toilet↗

NASA NTRSDate not supplied

Excavation of Exploration Toilet Fecal Canister from ISS Operations and Future Mission Impacts

Toilet↗

NASA NTRS1975

Performance of a hypersonic hot fuselage structure with a carbon dioxide frost projected, nonintegral cryogenic tank

A model which consisted of a hot structure and a nonintegral tank protected by a carbon dioxide frost thermal protection system was tested under the following conditions: (1) room temperature loading and (2) heating and loading corresponding to the Mach 8 flight of an air-breathing launch vehicle. In the simulated flight tests, liquid nitrogen inside the tank was withdrawn at the rate fuel would be consumed. Prior to each simulated flight test, carbon dioxide was cryodeposited in the insulation surrounding the tank; during the tests, subliming CO2 frost absorbed heat and provided a purge gas for the space between the tank and the structure. A method of flame spraying the joints between panels with a nickel-aluminum material was developed to prevent excessive leakage of the purge gas through the outer structure. The tests indicated that the hot structure (with a joint repaired by riveting), the nonintegral tank and suspension system, and the carbon dioxide frost thermal protection system provide a workable concept with predictable performance.

Sharpe, E. L.↗

NASA NTRS2005

Analysis of Heating Rates on the Conical Surface of Apollo Command Module Flying AS-202 Flight

The aerodynamic and aerothermal heating at the leeward surfaces of the Apollo capsule flying high angle of attack were found difficult to simulate using conventional tools. Due to the large subsonic region in the proximity of the shoulder of the base shield, correlation-based tools were found to be inadequate. CFD tools are too time consuming for conceptual design purposes, and cannot account for the transient effects of material response such as wall temperature and blowing. An accurate and timely simulation is essential to effectively size the thermal protection system (TPS), to enhance its performance, and to ensure the safety of the crew. Northrop Grumman Corporation applied a modified version of the MASCC/ATAC program, an inviscid flowfield code with boundary layer solver to simulate this scenario. The MASCC/ATAC code is believed to be the only non-CFD code that can rigorously perform the simulations on the windward surface. The predictions on the windward side of the conical surface were found to be in good agreement with flight data over a wide range of environments. The results are presented in the paper.

Wong, Jim L.↗

NASA NTRS2019

Sublimation Protection Coatings for Thermoelectric Materials for Space Power Applications

The compounds such as Yb14MnSb11 are relatively new p-type thermoelectric materials, respectively. NASA's interest in these material are to replace the state-of-the-art Si-Ge legs of the current radioisotope thermoelectric generators (RTGs). Ideally, the hot end of this leg would operate at 1000 degrees C in the vacuum of space. These materials, however, suffer from a high sublimation rate at elevated temperatures and would require a coating in order to survive the required RTG lifetime of 14 years. The purpose of present work is to develop sublimation protection coatings for Yb14MnSb11 at temperatures up to 1000 degrees C. Coatings for Yb14MnSb11 present many challenges. The coating must not significantly react or interdiffuse with the substrate thereby degrading the substrate or consuming the coating, must remain intact and not crack or spall during thermal cycling prior to launch, and must be a good insulator both electrically and thermally so as not to provide a short circuit for either electron flow or heat through the coating rather than through the leg. Based on these requirements, several oxides have been selected as possible coating candidates. This paper discusses the development of slurry processes to deposit these oxides coatings on thermoelectric materials.

Sublimation↗

NASA NTRS2013

Habitat Design Considerations for Implementing Solar Particle Event Radiation Protection

Radiation protection is an important habitat design consideration for human exploration missions beyond Low Earth Orbit. Fortunately, radiation shelter concepts can effectively reduce astronaut exposure for the relatively low proton energies of solar particle events, enabling moderate duration missions of several months before astronaut exposure (galactic cosmic ray and solar particle event) approaches radiation exposure limits. In order to minimize habitat mass for increasingly challenging missions, design of radiation shelters must minimize dedicated, single-purpose shielding mass by leveraging the design and placement of habitat subsystems, accommodations, and consumables. NASA's Advanced Exploration Systems RadWorks Storm Shelter Team has recently designed and performed radiation analysis on several low dedicated mass shelter concepts for a year-long mission. This paper describes habitat design considerations identified during the study's radiation analysis. These considerations include placement of the shelter within a habitat for improved protection, integration of human factors guidance for sizing shelters, identification of potential opportunities for habitat subsystems to compromise on individual subsystem performances for overall vehicle mass reductions, and pre-configuration of shelter components for reduced deployment times.

Simon, Mathew A.↗

NASA NTRSDate not supplied

Ultrashort Pulsed Laser Treatment: A Novel Sterilization Method for Planetary Protection

Introduction: On missions seeking signs of potential life elsewhere in the solar system, we have an obligation not to bring our own Earthly life with us. Reducing the bioburden (number of living microbes) on spacecraft is therefore required by the COSPAR Policy on Planetary Protection to target bodies that are of interest for understanding the origins of life (such as Mars). The method of spacecraft sterilization predominantly used by NASA is Heat Microbial Reduction, which is typically incompatible with heat-sensitive components such as optics and electronics, and is expensive and time-consuming. Here, we present preliminary results on a novel method for spacecraft hardware sterilization: high-intensity ultrashort (femtosecond) pulsed laser illumination. Femtosecond lasers use extremely high photon fluxes (10^29 photons/sec*cm^2, ~0.03 J/cm^2) in extremely short pulses, which can inactivate even stress-tolerant microbial spores with minimal damage to the spacecraft surface. This rapid sterilization technique could be carried out in situ in a spacecraft assembly clean room using high-speed surface scanning, saving critical time and resources. It also can potentially remove or reduce debris from inactivated cells and spores. Methods: To develop optimal laser processing parameters for inactivating planetary protection-relevant organisms on metal surfaces, we inoculated 1-cm^2 mirror-polished aluminum coupons with Bacillus subtilis spores (2x10^5 spores/coupon) and tested the effect of several parameters, including pulse count and fluence. Sterilization effectiveness was measured by recovering spores using a PVA (polyvinyl acetate) peel and conducting serial dilution and plating for colony-forming units (CFUs). Results: Our results show that pulse count and fluence both affect sterilization effectiveness and that within a certain pulse count range, increasing fluence increases effectiveness. We have demonstrated the ability to reduce viable microbial counts by at least 10^-4. Future work will include testing higher abundances and different species of microorganisms, effectiveness on complex surfaces, compatibility with sensitive surfaces, and quantification of cell debris removal. Femtosecond pulsed laser illumination has the potential to provide dramatic savings in both cost and schedule over current methods of bioburden reduction to prevent forward contamination. It may also have the potential for use in surface sterilization of returned samples to prevent back contamination.

Planetary Protection; Lasers; Sterilization; Bacil↗